ISO26262 concerns just only random hardware faults and systematic fault. SW tool development does not cover hardware, so it means that random hardware faults can be neglected.
In this case, I’d like to ask some questions. What’s difference between ASIL A qualified vs ASIL D qualified? You may answer that more technical methods are required in ASIL D. Right. And what else?
If there is no more differences except technical methods, then I will ask a question again. if all highly recommended methods are applied, then can I say that it is developed according to ASIL D, and it can be ASIL D qualifiable?
And I ask more, how can safety requirements be identified? Strictly speaking, SW safety requirements are only generated from technical safety requirements in the system level, but I don’t think that system level are considered during a SW tool development.
In this case, what should be safety requirements? how safety requirements can be identified?
Assuming that safety requirements are identified, why their ASIL allocation should be ASIL D?
Maybe, a tool vendor engineer would answer that they considered ASIL D to support for supplier’s ASIL D projects. In this case, if you consider ASIL A only and produce a tool. by the way, if you determine that you want to advertise that your tool is ASIL D qualified, then what are differences in the safety requirements aspect? maybe not.
if just technical methods are added for ASIL D, then is it sound that the tool is ASIL D qualified?
I rather recommend that it is useless to tag ASIL A/B/C/D for tool qualifications. No one want that their tool is ASIL B qualified more than ASIL D qualified.
Most of all persons who involved in a production related FuSa project in the automotive will know and, their opinion for this question might be same.
An author of a paper – “Effective management of functional safety for ISO 26262 standard” gives us an insight why they are hard to execute FuSa in the Automotive Domain.
I rather recommend you to read this paper regarding this topic. It is really well written.